Full-back Perch damaged his knee during the warm-up at Liverpool last Sunday, while central defender Mike Williamson broke a bone in his forearm while training in the gym this morning and was due to undergo surgery to repair it this afternoon.
Alan Pardew: "It's a freak injury and unfortunate for the big fella, and he is going to miss now the end part of the season.
"He has a slight weakness on that arm, which he has hurt before, so unfortunately, that has been the issue.
"Obviously, he is disappointed. He wanted to finish the season with us."